Rights statement: An edited version of this paper was published by AGU. Copyright 2018 American Geophysical Union. Lamy, L., Prangé, R., Tao, C., Kim, T., Badman, S. V., Zarka, P., et al. (2018). Saturn's northern aurorae at solstice from HST observations coordinated with Cassini's grand finale. Geophysical Research Letters, 45, 9353–9362. https://doi.org/10.1029/2018GL078211 To view the published open abstract, go to http://dx.doi.org and enter the DOI.
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Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
| <mark>Journal publication date</mark> | 28/09/2018 |
|---|---|
| <mark>Journal</mark> | Geophysical Research Letters |
| Issue number | 18 |
| Volume | 45 |
| Number of pages | 10 |
| Pages (from-to) | 9353-9362 |
| Publication Status | Published |
| Early online date | 17/07/18 |
| <mark>Original language</mark> | English |
Throughout 2017, the Hubble Space Telescope (HST) observed the northern far-ultraviolet aurorae of Saturn at northern solstice, during the Cassini Grand Finale. These conditions provided a complete viewing of the northern auroral region from Earth and a maximal solar illumination, expected to maximize the ionosphere-magnetosphere coupling. We analyze 24 HST images concurrently with Cassini measurements of Saturn's kilometric radiation and solar wind parameters predicted by two magnetohydrodynamic models. The aurorae reveal highly variable components, down to timescales of minutes, radiating 7 to 124 GW. They include a nightside-shifted main oval, unexpectedly frequent and bright cusp emissions, and a dayside low-latitude component. On average, these emissions display a strong local time dependence with two maxima at dawn and premidnight, the latter being newly observed and attributed to nightside injections possibly associated with solstice conditions. These results provide a reference frame to analyze Cassini in situ measurements, whether simultaneous or not.